Go to the Files option
Upload a file
Click on Files, Select the uploaded file and click on create Download
This brings up the Add Download page
Set title & Category
Access set by default to Public so set Access to other than public - in example to uploader-view
Then do Save & Close - do not use Save
Next use Downloads to give overview of the Downloads - access is set to Public, which was the default access setting, not to uploader-view.
If one repeats the process with another file and then does a Save, the Add Download page returns and one can change access to required setting. This time Save and Close is good.
Note that in my test the Access level of the selected Category was Public - maybe that is the 'challenge'.